Washing machine and control method therefor

ABSTRACT

A washing machine is provided. The washing machine includes a tub, a drum rotatably arranged within the tub, a drum motor for rotating the drum, a vibration sensor for sensing the vibration of the tub, and a control unit which maintains the rotation speed of the drum motor on the basis that the sensing value of the vibration sensor reaches a certain predetermined value during a dehydration operation, and which continuously maintains or increases the rotation speed of the drum motor based on the variation value of the sensing value of the vibration sensor.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application, claiming priority under § 365(c), of an International application No. PCT/KR2022/003225, filed on Mar. 8, 2022, which is based on and claims the benefit of a Korean patent application number 10-2021-0032970, filed on Mar. 12, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a washing machine for washing, rinsing and dehydrating clothes.

2. Description of Related Art

A washing machine may include a tub and a drum rotationally installed in the tub and do the laundry by rotating the drum containing clothes inside the tub. The washing machine may perform a washing course for washing the clothes, a rinsing course for rinsing the washed clothes, and a dehydrating course for dehydrating the clothes.

The dehydrating course may rotate the drum at about 1000 revolutions per minute (rpm) and separate water that has been soaked in the clothes from the clothes. As the drum spins fast during the dehydrating course, the tub receiving the drum may vibrate. When the clothes are not evenly spread inside the drum (i.e., there is an unbalance of the clothes), eccentricity of the rotating drum may occur. The eccentricity of the drum further increases vibration of the tub.

As such, when significant vibration and noise occurs due to the unbalance of the clothes contained in the drum during the dehydrating course of the washing machine, it may damage the washing machine, cause the user to feel discomfort and reduce dehydration efficiency.

The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide a washing machine capable of reducing vibration and noise occurring from unbalance of clothes during a dehydrating operation, and a method of controlling the same.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

In accordance with an aspect of the disclosure, a washing machine is provided. The washing machine includes a tub, a drum rotationally arranged in the tub, a drum motor configured to rotate the drum, a vibration sensor configured to detect vibration of the tub, and at least one processor configured to maintain rotation speed of the drum motor based on a sensing value of the vibration sensor reaching a certain value during a dehydrating operation, and keep maintaining or increasing the rotation speed of the drum motor based on a value of variation of the sensing value of the vibration sensor.

In accordance with another aspect of the disclosure, a method of controlling a washing machine is provided. The method includes driving a drum motor, obtaining a sensing value of a vibration sensor for detecting vibration of a tub during a dehydrating operation, maintaining rotation speed of the drum motor based on a sensing value of the vibration sensor reaching a preset certain value, and keeping maintaining or increasing the rotation speed of the drum motor based on a value of variation of the sensing value of the vibration sensor.

According to an embodiment of the disclosure, a washing machine and method for controlling the same may reduce vibration and noise occurring from a change in unbalance of clothes during a dehydrating operation.

According to an embodiment of the disclosure, a washing machine and method for controlling the same may reduce dispersion of vibration and noise occurring differently depending on an amount of clothes and a property of the clothes during a dehydrating operation. Hence, the user may feel the same level of vibration and noise whenever using the washing machine. Accordingly, discomfort otherwise felt by the user due to wide vibration and noise distributions may be eliminated.

Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an exterior view of a washing machine according to an embodiment of the disclosure;

FIG. 2 is a side cross-sectional view of a washing machine according to an embodiment of the disclosure;

FIG. 3 illustrates a configuration of a washing machine according to an embodiment of the disclosure;

FIG. 4 illustrates overall operations of a washing machine according to an embodiment of the disclosure;

FIG. 5 is a flowchart illustrating a dehydrating operation of a washing machine according to an embodiment of the disclosure;

FIG. 6 is a graph illustrating a mutual relation between sensing values of a vibration sensor and tub vibration displacements according to an embodiment of the disclosure;

FIG. 7 is a first graph representing a relation between sensing values of a vibration sensor and rotation speeds of a drum motor during dehydrating of a washing machine according to an embodiment of the disclosure;

FIG. 8 is a first table illustrating sensing values of a vibration sensor and rotation speed of a drum motor during a dehydrating operation in numerical values according to an embodiment of the disclosure;

FIG. 9 is a second graph representing a relation between sensing values of a vibration sensor and rotation speeds of a drum motor during dehydrating of a washing machine according to an embodiment of the disclosure;

FIG. 10 is a second table illustrating sensing values of a vibration sensor and rotation speed of a drum motor during a dehydrating operation according to an embodiment of the disclosure;

FIG. 11 is a graph representing vibration dispersion of a washing machine according to an embodiment of the disclosure; and

FIG. 12 is a graph representing noise dispersion of a washing machine according to an embodiment of the disclosure.

Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.

Like numerals refer to like elements throughout the specification. Not all elements of embodiments of the disclosure will be described, and description of what are commonly known in the art or what overlap each other in the embodiments will be omitted. The terms as used throughout the specification, such as “˜part”, “˜module”, “˜member”, “˜block”, or the like, may be implemented in software and/or hardware, and a plurality of “˜parts”, “˜modules”, “˜members”, or “˜blocks” may be implemented in a single element, or a single “˜part”, “˜module”, “˜member”, or “˜block” may include a plurality of elements.

It will be further understood that the term “connect” or its derivatives refer both to direct and indirect connection, and the indirect connection includes a connection over a wireless communication network.

The term “include (or including)” or “comprise (or comprising)” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps, unless otherwise mentioned.

Throughout the specification, when it is said that a member is located “on” another member, it implies not only that the member is located adjacent to the other member but also that a third member exists between the two members.

It will be understood that, although the terms first, second, third, or the like, may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section.

Reference numerals used for method steps are just used for convenience of explanation, but not to limit an order of the steps. Thus, unless the context clearly dictates otherwise, the written order may be practiced otherwise.

The principle and embodiments of the disclosure will now be described with reference to accompanying drawings.

FIG. 1 is an exterior view of a washer according to an embodiment of the disclosure. FIG. 2 is a side cross-sectional view of a washer according to an embodiment of the disclosure.

Referring to FIGS. 1 and 2 , the washing machine 100 may include a cabinet 101 and a door 102 arranged on the front of the cabinet 101. An inlet 101 a may be formed in the middle of the front side of the cabinet 101 to draw in or out the laundry (or also referred to as clothes). The door 102 may be provided to open or close the inlet 101 a. The door 102 may be mounted with a hinge to pivot on one side. That the inlet 101 a is closed by the door 102 may be detected by a door switch 103. When the inlet 101 a is closed and the washing machine 100 operates, the door 102 may be locked by a door lock 104.

The washing machine 100 may also include a control panel 110, a tub 120, a drum 130, a driver 140, a water supplier 150, a drain 160, a detergent supplier 170 and a vibration sensor 180 (180 a or 180 b).

The control panel 110 including an input for obtaining a user input and a display for displaying operation information of the washing machine 100 may be arranged in an upper portion of the front side of the cabinet 101. The control panel 110 may provide the user with a user interface to interact with the washing machine 100.

The tub 120 may be arranged inside the cabinet 101 and may contain water for washing and/or rinsing. The tub 120 may include tub front parts 121 with an opening 121 a formed on the front and tub rear parts 122 in the shape of a cylinder with a closed rear side. The opening 121 a through which to draw in or out clothes to or from the drum 130 may be formed on the tub front parts 121. A bearing 122 a is arranged on the rear wall of the tub rear parts 122 to rotationally fix a drum motor 141.

The drum 130 may be rotationally arranged in the tub 120 and may contain the clothes to be washed. The drum 130 may include a cylindrical drum body 131, drum front parts 132 arranged on the front of the drum body 131 and drum rear parts 133 arranged on the back of the drum body 131. The tub 120 and the drum 130 may be positioned at an angle to the ground. However, it is also possible that the tub 120 and the drum 130 are positioned to be parallel with the ground.

On the inner surface of the drum body 131, through holes 131 a connecting the inside of the drum 130 to the inside of the tub 120 and a lifter 131 b for lifting the clothes up the drum 130 during rotation of the drum 130 may be arranged. An opening 132 a through which to draw in or out clothes to or from the drum 130 may be formed on the drum front parts 132. The drum rear parts 133 may be connected to a shaft 141 a of the drum motor 141 that rotates the drum 130.

The drum motor 141 may rotate the drum 130. The drum motor 141 may include the driver 140. The drum motor 141 may be arranged on the outside of the tub rear parts 122 and connected to the drum rear parts 133 through the shaft 141 a. The shaft 141 a may penetrate the tub rear parts 122 and may be rotationally supported by the bearing 122 a arranged on the tub rear parts 122.

The drum motor 141 may include a stator 142 fixed on the outside of the tub rear parts 122 and a rotor 143 rotationally arranged and connected to the shaft 141 a. The rotor 143 may be rotated by magnetic interaction with the stator 142, and the rotation of the rotor 143 may be delivered to the drum 130 through the shaft 141 a. The drum motor 141 may include, for example, a brushless direct current motor (BLDC motor) or a permanent synchronous motor (PMSM) capable of easily controlling the rotation speed.

The water supplier 150 may supply water to the tub 120 and the drum 130. The water supplier 150 may include a water supply tube 151 connected to an external water source to supply water to the tub 120, and a water supply valve 152 arranged in the water supply tube 151. The water supply tube 151 may be arranged above the tub 120 and may extend to a detergent container 171 from the external water source. The water may flow to the tub 120 via the detergent container 171.

The water supply valve 152 may open or close the water supply tube 151 in response to an electric signal from a controller (for example, at least one processor) 190. In other words, the water supply valve 152 may allow or block the supply of water to the tub 120 from the external water source. The water supply valve 152 may include, for example, a solenoid valve that is opened or closed in response to an electric signal.

The drain 160 may drain out the water stored in the tub 120 and/or the drum 130. The drain 160 may include a drain tube 161 extending from the bottom of the tub 120 to the outside of the cabinet 101, and a drain pump 162 arranged at the drain tube 161. The drain pump 162 may pump the water in the drain tube 161 out of the cabinet 101.

The detergent supplier 170 may supply a detergent to the tub 120 and/or the drum 130. The detergent supplier 170 may be arranged above the tub 120 and may include the detergent container 171 and a mixing tube 172 that connects the detergent container 171 to the tub 120. The detergent container 171 may be connected to the water supply tube 151, and the water supplied through the water supply tube 151 may be mixed with the detergent in the detergent container 171. The mixture of the detergent and the water may be supplied to the tub 120 through the mixing tube 172.

The vibration sensor 180 (180 a or 180 b) may detect vibration of the tub 120. The vibration sensor 180 (180 a or 180 b) may be installed in at least one of a front position or rear position on the outer surface of the tub 120. In FIG. 2 , illustrated are the first vibration sensor 180 a arranged on an upper front surface of the tub 120 and the second vibration sensor 180 b arranged on an upper rear surface of the tub 120. The controller 190 may control the rotation speed of the drum motor 141 based on a sensing value of the vibration sensor 180.

The vibration sensor 180 may include an acceleration sensor for measuring 3-axis (X, Y and Z-axes) acceleration of the tub 120. For example, the vibration sensor 180 may be provided as a piezoelectric type, strain gauge type, piezoresistive type, capacitive type, servo type, or optical type acceleration sensor. In addition, the vibration sensor 180 may be provided as various sensors (e.g., gyroscope) capable of measuring vibration of the tub 120.

The vibration sensor 180 may output a sensing value of the vibration of the tub 120. For example, the vibration sensor 180 may output a constant value corresponding to the vibration of the tub 120. The vibration sensor 180 may output a voltage value corresponding to the 3-axis acceleration of the tub 120. The controller 190 of the washing machine 100 may determine a tub vibration displacement corresponding to the sensing value of the vibration sensor 180, and control the rotation speed of the drum motor 141 based on the tub vibration displacement.

Alternatively, the vibration sensor 180 may output the tub vibration displacement corresponding to a change in 3-axis acceleration. The controller 190 may determine rotation speed of the drum motor 141 based on the tub vibration displacement, which is the sensing value received from the vibration sensor 180.

The vibration sensor 180 may be provided as a micro electro mechanical system (MEMS) sensor. A MEMS is a scheme developed with the advancement of semiconductor technologies, and the MEMS sensor may be made by deposition, photolithographic patterning and etching processes. The vibration sensor 180 may be formed with various materials, such as silicon, polymer, metal or ceramic. The vibration sensor 180 manufactured in the MEMS scheme may have a size in micrometers.

FIG. 3 illustrates a configuration of a washing machine according to an embodiment of the disclosure.

Referring to FIG. 3 , the washing machine 100 may include not only the mechanical components as described in connection with FIGS. 1 and 2 but also electrical components. The washing machine 100 may include the door switch 103, the door lock 104, the control panel 110, the drum motor 141, the water supply valve 152, the drain pump 162, the vibration sensor 180 and the controller 190. The controller 190 may be electrically connected to the components of the washing machine 100 to control the respective components.

The door switch 103 may detect a closed state of the door 102 and an open state of the door 102. For example, the door switch 103 may be opened (turned off) in the open state of the door 102 and closed (turned on) in the closed state of the door 102. The door switch 103 may transmit a signal indicating the closed state of the door 102 or a signal indicating the open state of the door 102 to the controller 190.

The door lock 104 may lock the door 102 in response to a locking signal from the controller 190. For example, when the door 102 closes the inlet 101 a and the washer 100 operates, the controller 190 may control the door lock 104 to lock the door 102.

The control panel 110 may include an input button for obtaining a user input, and a display for displaying a laundry setting and/or laundry operation information in response to the user input. The control panel 110 may provide the user with a user interface to interact with the washing machine 100. The input button may include, for example, a power button, a start button, a course selection dial, and a detailed setting button. The input button may also include a tact switch, a push switch, a slide switch, a toggle switch, a micro switch, or a touch switch.

The display may include a screen for displaying a laundry course selected by turning the course selection dial and an operation time of the washing machine 100, and an indicator for indicating detailed settings selected by the setting button. The display may include, for example, a liquid crystal display (LCD) panel and/or a light emitting diode (LED).

The laundry course may include preset washing settings (e.g., laundry temperature, the number of rinsing times, and dehydration intensity) depending on the type of clothes (e.g., shirts, pants, underwear, or bedclothes), the texture of the clothes (e.g., cotton, polyester or wool) and an amount of the clothes. For example, a standard laundry course may include universal laundry settings for clothes. A bedcloth laundry course may include laundry settings optimized to wash bedclothes. There may be various laundry courses, such as standard washing, powerful washing, wool washing, bedclothes washing, infant clothes washing, towel washing, minimal washing, boiling washing, economic washing, outdoor clothes washing, rinsing plus dehydrating, dehydrating, or the like.

The driver 140 may include the drum motor 141 and a driving circuit 200. The driving circuit 200 may apply a driving current to the drum motor 141 for driving the drum motor 141 in response to a driving signal (a motor control signal) of the controller 190. The driving circuit 200 may rectify and convert alternate current (AC) power from an external power source to direct current (DC) power, and convert the DC power to sinusoidal driving power. The driving circuit 200 may include an inverter for outputting the converted driving power to the drum motor 141. The inverter may include a plurality of switching devices, and open (turn off) or close (turn on) the plurality of switching devices based on a driving signal from the controller 190. A driving current may be applied to the drum motor 141 according to the opening or closing of the switching devices. Furthermore, the driving circuit 200 may include a current sensor (not shown) for measuring a driving current output from the inverter.

The controller 190 may calculate rotation speed of the drum motor 141 based on an electrical angle of the rotor. The electrical angle of the rotor may be obtained from a position sensor (not shown) equipped on the drum motor 141. For example, the controller 190 may calculate the rotation speed of the drum motor 141 based on an extent of a change in the electrical angle of the rotor for a sampling time interval. The position sensor may be implemented by a hall sensor, an encoder, or a resolver that is able to measure a position of the rotor 143 of the drum motor 141. Furthermore, the controller 190 may calculate the rotation speed of the drum motor 141 based on a driving current value measured by the current sensor (not shown).

the drum motor 141 may rotate the drum 130 under the control of the controller 190. The controller 190 may drive the drum motor 141 to follow a target rotation speed.

The water supply valve 152 may be opened in response to a water supply signal from the controller 190. As the water supply valve 152 is opened, water may be supplied into the tub 120 through the water supply tube 151.

The drain pump 162 may discharge the water out of the cabinet 101 through the drain tube 161 in response to a drain signal from the controller 190. By the operation of the drain pump 162, the water stored in the tub 120 may be discharged out of the cabinet 101 through the drain tube 162.

The vibration sensor 180 may detect vibration of the tub 120. Specifically, the vibration sensor 180 may detect vibration of the tub 120 caused by rotation of the drum 130 during the dehydrating course. Unbalance of clothes spread in the drum 130 may cause eccentricity of the drum 130, which may in turn cause a vibration of the tub 120. When the rotation speed of the drum motor 141 increases while the spreading of clothes is unbalanced, vibration of the tub 120 and the vibration noise may increase as well.

The vibration sensor 180 may output a sensing value of the vibration of the tub 120. For example, the vibration sensor 180 may output a constant value corresponding to the vibration of the tub 120. Alternatively, the vibration sensor 180 may output a 3-axis (X, Y, and Z-axes) acceleration value of the tub 120, a voltage value corresponding to the acceleration value and/or a tub vibration displacement corresponding to the acceleration value. The controller 190 may determine a rotation speed of the drum motor 141 based on the sensing value of the vibration sensor 180.

The tub vibration displacement may be defined, when the tub 120 is vibrated, as amplitude of the vibration. The controller 190 may monitor the sensing value of the vibration sensor 180 at preset intervals while dehydrating is going on in the washing machine 100. Specifically, the controller 190 may constantly receive the sensing value of the vibration sensor 180 until the end of the dehydrating operation, and based on the sensing value of the vibration sensor 180, control the rotation speed of the drum motor 141.

The controller 190 may include a processor 191 for generating a control signal for an operation of the washing machine 100, and a memory 192 for storing a program, an application, instructions and/or data for operation of the washing machine 100. The processor 191 and the memory 192 may be implemented with separate semiconductor devices or in a single semiconductor device. Furthermore, the controller 190 may include a plurality of processors or a plurality of memories. The controller 190 may be provided in various positions inside the washing machine 100. For example, the controller 190 may be included in a printed circuit board (PCB) arranged in the control panel 110.

The processor 191 may include an operation circuit, a storage circuit, and a control circuit. The processor 191 may include one or multiple chips. Furthermore, the processor 191 may include one or multiple cores.

The memory 192 may store a program for performing a laundry operation according to a laundry course and data including a laundry setting according to the laundry course. Furthermore, the memory 192 may store a laundry course and a laundry setting currently selected based on a user input. The memory 192 may include a volatile memory, such as a static random access memory (S-RAM) or a dynamic RAM (D-RAM), and a non-volatile memory, such as a read only memory (ROM) or an erasable programmable ROM (EPROM). The memory 192 may include a memory device, or multiple memory devices.

The processor 191 may process data and/or a signal based on the program provided from the memory 192, and transmit a control signal to each component of the washing machine 100 based on the processing result. For example, the processor 191 may process a user input received through the control panel 110. The processor 191 may output a control signal to control the door lock 104, the drum motor 141(104) water supply valve 152, and the drain pump 162 in response to a user input.

The processor 191 may control the drum motor 141, the water supply valve 152 and the drain pump 162 to perform a washing course, a rinsing course and a dehydrating course. Furthermore, the processor 191 may control the control panel 110 to display a laundry setting and laundry operation information. The processor 191 may control the vibration sensor 180 to detect vibration of the tub 120 during the dehydrating operation.

FIG. 4 illustrates overall operations of a washing machine according to an embodiment of the disclosure.

Referring to FIG. 4 , the washing machine 100 may sequentially perform a washing course 1010, a rinsing course 1020 and a dehydrating course 1030 according to a user input. Clothes may be washed in the washing course 1010. Dirt on the clothes may be separated by chemical actions of a detergent and/or mechanical actions, such as falling.

The washing course 1010 may include laundry measurement 1011 for measuring an amount of clothes, water supply 1012 for supplying water into the tub 120, washing 1013 for washing the clothes by rotating the drum 130 at low speed, draining 1014 for draining water contained in the tub 120, and intermediate dehydrating 1015 for separating water from the clothes by rotating the drum 130 at high speed.

In the process of the washing 1013, the controller 190 may rotate the drum motor 141 in forward direction or reverse direction. Due to the rotation of the drum 130, the clothes may fall down the drum 130.

In the process of the intermediate dehydrating 1015, the controller 190 may rotate the drum motor 141 at high speed. Due to the high-speed rotation of the drum 130, water may be separated from the clothes.

The rotation speed of the drum 130 may increase stepwise during the intermediate dehydrating 1015. As the rotation speed of the drum 130 increases, vibration of the tub 120 may increase as well, and there may be a change in the sensing value of the vibration sensor 180. The controller 190 may control the rotation speed of the drum motor 141 based on the sensing value of the vibration sensor 180.

The controller 190 may maintain the rotation speed of the drum motor 141 based on the sensing value of the vibration sensor 180 reaching a certain value. In other words, the controller 190 may control the drum motor 141 to maintain the rotation speed determined at a time when the sensing value of the vibration sensor 180 reaches a certain value. The rotation speed determined at a time when the sensing value of the vibration sensor 180 reaches the certain value may be referred to as a first rotation speed.

The certain value is a value corresponding to a maximum tolerable vibration displacement of the tub 120 during the dehydrating, which may also be referred to as a ‘tolerable unbalance value’. The certain value may be set to various values depending on the design. For example, the certain value may be selected differently depending on the amount and type of the clothes.

When the sensing value of the vibrating sensor 180 reaches the certain value after the start of dehydrating, the controller 190 may maintain the rotation speed of the drum motor 141 determined at a time when the sensing value of the vibration sensor 180 reaches the certain value.

The controller 190 may keep maintaining or increase the rotation speed of the drum motor 141 based on a value of variation of the sensing value of the vibration sensor 180. For example, the controller 190 may keep maintaining the first rotation speed of the drum motor 141 based on the value of variation of the sensing value of the vibration sensor 180 smaller than preset delta constant δ. The delta constant δ may be set to various values depending on the design. The delta constant δ may be selected differently depending on the amount and type of the clothes.

Furthermore, the controller 190 may increase the rotation speed of the drum motor 141 based on the sensing value of the vibration sensor 180 reduced from the certain value by the preset delta constant δ. The controller 190 may control the drum motor 141 to maintain the increased rotation speed (second rotation speed) based on the sensing value of the vibration sensor 180 reaching the certain value again with an increase in rotation speed of the drum motor 141. In other words, the controller 190 may control the drum motor 141 to maintain the rotation speed (second rotation speed) higher than the previous rotation speed (first rotation speed). The second rotation speed may be determined at a time when the sensing value of the vibration sensor 180 reaches the certain value again.

The controller 190 may keep maintaining the increased rotation speed of the drum motor 141 or increase the rotation speed of the drum motor 141 based on a value of variation of the sensing value of the vibration sensor 180. The controller 190 may constantly determine whether to maintain or increase the rotation speed of the drum motor 141 based on the value of variation of the sensing value of the vibration sensor 180 until the end of the dehydrating.

The clothes may be rinsed in the rinsing course 1020. Specifically, the remnant of the detergent or dirt on the clothes may be removed. The rinsing course 1020 may include water supply 1021 for supplying water into the tub 120, rinsing 1022 for rinsing the clothes by driving the drum 130, draining 1023 for draining water contained in the tub 120, and intermediate dehydrating 1024 for separating water from the clothes by driving the drum 130.

The water supply 1021, draining 1023 and intermediate dehydrating 1024 of the rinsing course 1020 may correspond to the water supply 1012, draining 1014 and intermediate dehydrating 1015 of the washing course 1010. During the rinsing course 1020, the water supply 1021, the rinsing 1022, the draining 1023 and the intermediate dehydrating 1024 may be performed one or multiple times.

Water contained in the clothes may be separated from the clothes according to the dehydrating course 1030. The water may be separated from the clothes by high-speed rotation of the drum 130, and the separated water may be discharged out of the washing machine 100. The dehydrating course 1030 may include final dehydrating 1031 to separate water from the clothes by rotating the drum 130 at high speed. With the final dehydrating 1031, the last intermediate dehydrating 1024 of the rinsing course 1020 may be skipped.

For the final dehydrating 1031, the controller 190 may control the driving circuit 200 to rotate the drum motor 141 at high speed. Due to the high-speed rotation of the drum 130, water may be separated from the clothes contained in the drum 130 and drained out of the washing machine 100. As the operation of the washing machine 100 is completed with the final dehydrating 1031, performance time of the final dehydrating 1031 may be longer than performance time of the intermediate dehydrating 1015 or 1024.

The rotation speed of the drum motor 141 may increase stepwise during the final dehydrating 1031. Similar to the rotation speed of the drum motor 141 controlled in the intermediate dehydrating 1015 of the washing course 1010, rotation speed of the drum motor 141 may be controlled based on the sensing value of the vibration sensor 180 even in the final dehydrating 1031. Specifically, the controller 190 may maintain the rotation speed of the drum motor 141 based on the sensing value of the vibration sensor 180 reaching a certain value. In other words, the controller 190 may control the drum motor 141 to maintain the first rotation speed determined at a time when the sensing value of the vibration sensor 180 reaches the certain value.

For example, the certain value is a value corresponding to a maximum tolerable vibration displacement of the tub 120 during the dehydrating, which may also be referred to as a ‘tolerable unbalance value’. The certain value may be set to various values depending on the design. For example, the certain value may be selected differently depending on the amount and type of the clothes.

The controller 190 may keep maintaining or increase the rotation speed of the drum motor 141 based on a value of variation of the sensing value of the vibration sensor 180. For example, the controller 190 may keep maintaining the first rotation speed of the drum motor 141 based on the value of variation of the sensing value of the vibration sensor 180 smaller than preset delta constant δ. The delta constant δ may be set to various values depending on the design. The delta constant δ may be selected differently depending on the amount and type of the clothes.

Furthermore, the controller 190 may increase the rotation speed of the drum motor 141 based on the sensing value of the vibration sensor 180 reduced from the certain value by the preset delta constant δ. The controller 190 may control the drum motor 141 to maintain the increased rotation speed based on the sensing value of the vibration sensor 180 reaching the certain value again with an increase in rotation speed of the drum motor 141. In other words, the controller 190 may control the drum motor 141 to maintain the rotation speed (second rotation speed) higher than the previous rotation speed (first rotation speed). The second rotation speed may be determined at a time when the sensing value of the vibration sensor 180 reaches the certain value again.

The controller 190 may keep maintaining the increased rotation speed of the drum motor 141 or increase the rotation speed of the drum motor 141 based on a value of variation of the sensing value of the vibration sensor 180. The controller 190 may constantly determine whether to maintain or increase the rotation speed of the drum motor 141 based on the value of variation of the sensing value of the vibration sensor 180 until the end of the dehydrating.

As described above, the washing machine 100 may perform the washing course 1010, the rinsing course 1020 and the dehydrating course 1030 to do the laundry. During the intermediate dehydrating 1015 or 1024 and the final dehydrating 1031 in particular, the controller 190 of the washing machine 100 may increase the rotation speed of the drum motor 141 that rotates the drum 130 stepwise. The controller 190 may maintain or increase the rotation speed of the drum motor 140 based on the sensing value of the vibration sensor 180.

FIG. 5 is a flowchart illustrating a dehydrating operation 500 of a washing machine according to an embodiment of the disclosure. FIG. 6 is a graph 600 illustrating a mutual relation between sensing values of a vibration sensor and tub vibration displacements according to an embodiment of the disclosure. The dehydrating operation 500 of the washing machine 100 will now be described below.

The dehydrating operation 500 may include the intermediate dehydrating 1015 or 1024 and the final dehydrating 1031 as described in FIG. 4 .

Referring to FIG. 5 , the washing machine 100 begins dehydrating, in operation 501. The controller 190 may control the drain pump 162 to drain the water in the tub 120 after the washing 1013 or the rinsing 1022. The controller 190 may determine whether there is water left in the tub 120 based on the output of a water level sensor (not shown). The controller 190 may operate the drum motor 141 once all the water in the tub 120 is drained to the outside.

The controller 190 may increase the rotation speed of the drum motor 141, in operation 502. The controller 190 may rotate the drum 130 by driving the drum motor 141 to dehydrate the clothes located in the drum 130. The rotation speed of the drum motor 141 may increase stepwise during the dehydrating operation 500.

As described above, vibration and noise of the tub 120 may occur due to unbalance of the clothes in the drum 130. The unbalance of the clothes may occur due to moisture unevenly contained in the clothes. When the rotation speed of the drum motor 141 increases while the clothes are in the unbalanced state in the drum 130, vibration and noise of the tub 120 may increase. When the vibration of the tub 120 is excessive, it may cause damage to the washing machine 100 and reduce dehydration efficiency.

Accordingly, to reduce the vibration and noise of the tub 120 during the dehydrating process, the controller 190 may monitor the sensing value of the vibration sensor 180 while dehydration is going on, and control the rotation speed of the drum motor 141 not to make too much vibration of the tub 120.

The controller 190 may receive an output of the vibration sensor 180, in operation 503. For example, the sensing value of the vibration sensor 180 may be a constant value corresponding to the vibration of the tub 120. The sensing value of the vibration sensor 180 may be output as an acceleration value or a voltage value corresponding to the acceleration value. The sensing value of the vibration sensor 180 may have a preset mutual relation with the vibration displacement of the tub 120.

Referring to FIG. 6 , a graph 600 illustrates that the tub vibration displacement may be proportional to the sensing value of the vibration sensor 180. In other words, as the sensing value of the vibration sensor 180 increases, the tub vibration displacement may be determined to have a larger value. Data of the mutual relation between the sensing value of the vibration sensor 180 and the tub vibration displacement may be stored in the memory 192 of the controller 190, and the processor 191 may determine the tub vibration displacement by making use of the mutual relation data and the sensing value of the vibration sensor 180.

Unlike this, the vibration sensor 180 may output the tub vibration displacement by using a mutual relation between the acceleration value and the tub vibration displacement. In this case, the controller 190 may control the drum motor 141 based on the tub vibration displacement received from the vibration sensor 180.

The controller 190 may detect whether the sensing value of the vibration sensor 180 reaches a certain value, in operation 504. For example, the certain value is a value corresponding to a maximum tolerable vibration displacement of the tub 120 during the dehydrating, which may also be referred to as a ‘tolerable unbalance value’. The certain value may be set to various values depending on the design. For example, the certain value may be selected differently depending on the amount and type of the clothes.

The controller 190 may maintain the rotation speed of the drum motor 141 based on the sensing value of the vibration sensor 180 reaching the certain value, in operation 505. Maintaining the rotation speed of the drum motor 141 may refer to maintaining the drum motor 141 at a constant rotation speed or maintaining the rate of increase in rotation speed of the drum motor 141 at or below a preset marginal rate of increase. The marginal rate of increase may be set to a very small value to prevent the sensing value of the vibration sensor 180 from exceeding a certain value. Maintaining the rotation speed of the drum motor 141 may prevent the sensing value of the vibration sensor 180 from exceeding a certain value Da.

The controller 190 may determine whether dehydrating is finished, in operation 506. For example, when a set dehydrating time is expired, the dehydrating is determined to be ended. When the dehydrating is ended, the controller 190 may stop driving the drum motor 141 and terminate the dehydrating operation. However, before completion of the dehydrating, the controller 190 may keep maintaining or increase the rotation speed of the drum motor 141 based on a value of variation of the sensing value of the vibration sensor 180.

The controller 190 may determine whether the value of variation of the sensing value of the vibration sensor 180 reaches the preset delta constant δ, in operation 507. While the drum motor 141 is operating at a rotation speed determined at a time when the sensing value of the vibration sensor 180 reaches the certain value, water separated from the clothes is discharged outside and the sensing value of the vibration sensor 180 may be reduced. In other words, when the water comes out from the clothes, the unbalance of the clothes may be reduced and accordingly, the vibration of the tub 120 may be reduced. Accordingly, when the sensing value of the vibration sensor 180 decreases, the rotation speed of the drum motor 141 may need to be further increased.

When the value of variation of the sensing value of the vibration sensor 180 is smaller than the preset delta constant δ, the controller 190 may keep maintaining the rotation speed of the drum motor 141 until the end of dehydrating in 507 and 505 without further increasing the rotation speed of the drum motor 141. When the value of variation of the sensing value of the vibration sensor 180 is smaller than the preset delta constant δ, the controller 190 may determine that a margin of increasing the rotation speed of the drum motor 141 is short.

When the sensing value of the vibration sensor 180 is reduced from the certain value Da by the preset delta constant δ, the controller 190 may further increase the rotation speed of the drum motor 141, in 507 and 502. Specifically, when the sensing value of the vibration sensor 180 is reduced by the delta constant δ as the water contained in the clothes comes out, i.e., when the sensing value reaches a lower limit Db, the controller 190 may increase the rotation speed of the drum motor 141 until the sensing value of the vibration sensor 180 reaches the certain value Da again. From when the sensing value of the vibration sensor 180 reaches the certain value Da again, the increased rotation speed of the drum motor 141 may be maintained.

The controller 190 may keep maintaining the increased rotation speed of the drum motor 141 or increase the rotation speed of the drum motor 141 based on a value of variation of the sensing value of the vibration sensor 180. The controller 190 may constantly determine whether to maintain or increase the rotation speed of the drum motor 141 based on the value of variation of the sensing value of the vibration sensor 180 until the end of the dehydrating.

FIG. 7 is a first graph 700 representing a relation between sensing values of a vibration sensor and rotation speeds of a drum motor during dehydrating of a washing machine according to an embodiment of the disclosure. FIG. 8 is a first table 800 illustrating sensing values of a vibration sensor and rotation speed of a drum motor during a dehydrating operation in numerical values according to an embodiment of the disclosure.

Referring to the first graph 700 of FIG. 7 and the first table 800 of FIG. 8 , the controller 190 may control the drum motor 141 to be maintained at a first rotation speed V1 determined at a first time t1 when the sensing value of the vibration sensor 180 reaches the certain value Da for the first time. For example, the certain value Da may be set to 760, and the first rotation speed V1 of the drum motor 141 may be maintained at 800 rpm from the first time t1.

While the drum motor 141 is operating at the first rotation speed V1, water separated from the clothes is drained out and thus the sensing value of the vibration sensor 180 may be reduced. The controller 190 may maintain the rotation speed of the drum motor 141 at 800 rpm until a second time t2 at which the sensing value of the vibration sensor 180 is reduced from the certain value Da by the delta constant δ. For example, the delta constant δ may be 150, and the sensing value of the vibration sensor 180 may be 610 at the second time t2.

The controller 190 may increase the rotation speed of the drum motor 141 from the second time t2. When the rotation speed of the drum motor 141 increases, vibration of the tub 120 may increase again, and the sensing value of the vibration sensor 180 may increase accordingly. The controller 190 may control the drum motor 141 to be maintained at an increased second rotation speed V2, i.e., 900 rpm, from a third time t3 at which the sensing value of the vibration sensor 180 reaches the certain value Da again.

In the first graph 700, as the sensing value of the vibration sensor 180 is not reduced after the third time t3, the controller 190 may operate the drum motor 141 at the second rotation speed V2 of 900 rpm until the end the of the dehydrating.

FIG. 9 is a second graph 900 representing a relation between sensing values of a vibration sensor and rotation speeds of a drum motor during dehydrating of a washing machine according to an embodiment of the disclosure. FIG. 10 is a second table 1000 illustrating sensing values of a vibration sensor and rotation speed of a drum motor during a dehydrating operation according to an embodiment of the disclosure.

Referring to the second graph 900 of FIG. 9 and the second table 1000 of FIG. 10 , the certain value Da may be set to 900, and the delta constant δ may be preset to 150. The first rotation speed V1 of the drum motor 141 determined at the first time t1 at which the sensing value of the vibration sensor 180 reaches the certain value Da for the first time may be 850 rpm. The controller 190 may maintain the rotation speed of the drum motor 141 at 850 rpm until the second time t2 at which the sensing value of the vibration sensor 180 is reduced by the delta constant δ to 750 (Db).

The controller 190 may increase the rotation speed of the drum motor 141 from the second time t2. With the increase in rotation speed of the drum motor 141, the sensing value of the vibration sensor 180 may increase to reach the certain value Da again. The controller 190 may control the drum motor 141 to be maintained at an increased second rotation speed V2, i.e., 900 rpm, from a third time t3 at which the sensing value of the vibration sensor 180 reaches the certain value Da again.

The controller 190 may maintain the rotation speed of the drum motor 141 at 900 rpm until a fourth time t4 at which the sensing value of the vibration sensor 180 is reduced from the certain value Da by the delta constant δ. When the sensing value of the vibration sensor 180 is reduced again by the delta constant δ to 750 (Db), the controller 190 may further increase the rotation speed of the drum motor 141 from the fourth time to a fifth time, t5, at which the sensing value of the vibration sensor 180 reaches the certain value Da again. From the fifth time t5, the controller 190 may control the drum motor 141 to maintain an increased third rotation speed V3, which is 1000 rpm. In the second graph 900, as the sensing value of the vibration sensor 180 is not reduced after the fifth time t5, the controller 190 may operate the drum motor 141 at the third rotation speed V3 of 1000 rpm until the end the of the dehydrating, te.

As such, the washing machine 100 according to an embodiment may constantly control the drum motor 141 to reach the final rotation speed in the dehydrating process, and may even variably apply the final rotation speed of the drum 130 for dehydrating. In other words, the washing machine 100 according to an embodiment may reduce vibration and noise of the tub 120 occurring during dehydrating and also reduce dispersion of the vibration and noise occurring differently depending on the amount and property of the clothes by controlling the drum motor 141 based on unbalance of the clothes that varies during the dehydrating.

FIG. 11 is a graph 1100 representing vibration dispersion of a washing machine according to an embodiment of the disclosure. FIG. 12 is a graph 1200 representing noise dispersion of a washing machine according to an embodiment of the disclosure.

Referring to FIGS. 11 and 12 , in a comparative example, the washing machine determines unbalance of clothes only in the beginning of dehydrating and determines a maximum rotation speed of the drum depending on an extent (value) of the unbalance determined in the beginning of the dehydrating, in which case the washing machine has large vibration dispersion and noise dispersion. In the comparison example, the washing machine does not constantly determine the unbalance of the clothes that varies while the dehydrating is going on and does not change the maximum rotation speed of the drum according to a change in vibration of the tub, so the user may feel the vibration and noise of the washing machine differently each time the washing machine is used. The vibration and noise of the washing machine felt differently at each time of use may lower confidence of the user in the product.

On the other hand, the washing machine and method for controlling the washing machine according to an embodiment of the disclosure may constantly monitor vibration of the tub 120 during the dehydrating operation and control the rotation speed of the drum 130 stepwise according to a change in vibration of the tub 120, thereby reducing vibration and noise occurring from a change in unbalance of the clothes.

Furthermore, according to an embodiment of the disclosure, a washing machine and method for controlling the same may reduce dispersion of vibration and noise occurring differently depending on an amount of clothes and a property of the clothes during the dehydrating operation. Accordingly, the user may feel the same level of vibration and noise whenever using the washing machine. Accordingly, discomfort otherwise felt by the user due to wide vibration and noise dispersion may be eliminated.

Meanwhile, the embodiments of the disclosure may be implemented in the form of a recording medium for storing instructions to be carried out by a computer. The instructions may be stored in the form of program codes, and when executed by a processor, may generate program modules to perform operations in the embodiments of the disclosure. The recording media may correspond to computer-readable recording media.

The computer-readable recording medium includes any type of recording medium having data stored thereon that may be thereafter read by a computer. For example, it may be a ROM, a RAM, a magnetic tape, a magnetic disk, a flash memory, an optical data storage device, or the like.

The computer-readable storage medium may be provided in the form of a non-transitory storage medium. The term ‘non-transitory storage medium’ may mean a tangible device without including a signal, e.g., electromagnetic waves, and may not distinguish between storing data in the storage medium semi-permanently and temporarily. For example, the non-transitory storage medium may include a buffer that temporarily stores data.

In an embodiment of the disclosure, the aforementioned method according to the various embodiments of the disclosure may be provided in a computer program product. The computer program product may be a commercial product that may be traded between a seller and a buyer. The computer program product may be distributed in the form of a storage medium (e.g., a compact disc read only memory (CD-ROM)), through an application store (e.g., Play store™), directly between two user devices (e.g., smart phones), or online (e.g., downloaded or uploaded). In the case of online distribution, at least part of the computer program product (e.g., a downloadable app) may be at least temporarily stored or arbitrarily created in a storage medium that may be readable to a device, such as a server of the manufacturer, a server of the application store, or a relay server.

While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents. 

What is claimed is:
 1. A washing machine comprising: a tub; a drum rotationally arranged in the tub; a drum motor configured to rotate the drum; a vibration sensor configured to detect vibration of the tub; and at least one processor configured to: maintain rotation speed of the drum motor based on a sensing value of the vibration sensor reaching a certain value during a dehydrating operation, and keep maintaining or increase the rotation speed of the drum motor based on a value of variation of the sensing value of the vibration sensor.
 2. The washing machine of claim 1, wherein the at least one processor is further configured to keep maintaining the rotation speed of the drum motor based on a value of variation of the sensing value of the vibration sensor smaller than a preset delta constant.
 3. The washing machine of claim 1, wherein the at least one processor is further configured to increase the rotation speed of the drum motor based on a sensing value of the vibration sensor reduced from the certain value by a preset delta constant.
 4. The washing machine of claim 3, wherein the at least one processor is further configured to: based on the sensing value of the vibration sensor reaching the certain value again with the increase in rotation speed of the drum motor, control the drum motor to maintain the increased rotation speed; and keep maintaining the increased rotation speed of the drum motor or further increase the rotation speed of the drum motor based on a value of variation of the sensing value of the vibration sensor.
 5. The washing machine of claim 1, wherein the at least one processor is further configured to monitor a sensing value of the vibration sensor at preset intervals.
 6. The washing machine of claim 1, wherein the at least one processor is further configured to select the certain value based on an amount of laundry and a type of the laundry.
 7. The washing machine of claim 2, wherein the at least one processor is further configured to select the preset delta constant based on an amount of laundry and a type of the laundry.
 8. The washing machine of claim 1, wherein the vibration sensor comprises an acceleration sensor configured to measure 3-axis acceleration of the tub, and wherein the vibration sensor is installed in at least one of a front position or a rear position on an outer surface of the tub.
 9. A method of controlling a washing machine, the method comprising: driving a drum motor; obtaining a sensing value of a vibration sensor for detecting vibration of a tub during a dehydrating operation; maintaining rotation speed of the drum motor based on a sensing value of the vibration sensor reaching a preset certain value; and keeping maintaining or increasing the rotation speed of the drum motor based on a value of variation of the sensing value of the vibration sensor.
 10. The method of claim 9, wherein the keeping maintaining of the rotation speed of the drum motor is determined based on the value of variation of the sensing value of the vibration sensor smaller than a preset delta constant.
 11. The method of claim 9, wherein the increasing of the rotation speed of the drum motor is determined based on the sensing value of the vibration sensor reduced from the preset certain value by a preset delta constant.
 12. The method of claim 11, wherein the keeping maintaining or increasing of the rotation speed of the drum motor comprises: based on the sensing value of the vibration sensor reaching the preset certain value again with the increase in rotation speed of the drum motor, controlling the drum motor to maintain the increased rotation speed; and keeping maintaining the increased rotation speed of the drum motor or further increasing the rotation speed of the drum motor based on a value of variation of the sensing value of the vibration sensor.
 13. The method of claim 9, wherein the obtaining of the sensing value of the vibration sensor comprises monitoring the sensing value of the vibration sensor at preset intervals.
 14. The method of claim 9, wherein the preset certain value is selected based on an amount of laundry and a type of the laundry.
 15. The method of claim 10, wherein the preset delta constant is selected based on an amount of laundry and a type of the laundry. 